The invention pertains to concrete highway joint systems utilizing interconnecting embedded bars and other features to prevent misalignment of the joints during highway section expansion and contraction.
The majority of the nation's major highways, particularly those highways built for heavy high speed traffic, such as those included in the interstate system, are formed of concrete. Typical concrete highway construction includes the formation of a plurality of sections joined with an expansion joint perpendicularly disposed to the longitudinal length of the sections. It is known to use interlocking configurations at the highway section ends, and dowel bars, in order to prevent "buckling" and other misalignment problems that often occur as the highway sections expand and contract under temperature fluctuations. Considerable difficulty has been encountered in preventing damage to concrete highways due to such expansion and contraction, and the maintenance costs on concrete highways due to buckling, formation of cracks, and the like, amounts to many millions of dollars annually.
As mentioned above, the use of dowel bars to control the alignment of highway sections is known as shown in U.S. Pat. Nos. 2,106,095 and 2,262,677. Tongue and groove type joints have also been utilized as shown in U.S. Pat. Nos. 1,546,005; 1,571,700; 3,437,018 and 3,628,764. Further, tongue and groove joints employed in combination with dowel bars are known as shown in U.S. Re. Pat. No. 24,921, U.S. Pat. Nos. 3,143,783 and 3,785,741. However, the joint constructions of patents such as forementioned have not prevented those problems which have existed in concrete highway construction and the search for an improved joint has continued.
In the installation of divider plates between adjacent sections it is common to mount the plate upon a wire "basket" as shown in U.S. Pat. Nos. 2,308,677 and 2,296,195. However, such basket constructions require assembly and manufacture at a location remote from the site of use, and transportation and handling is expensive and troublesome.
While the majority of concrete highway joints are perpendicularly disposed to the length of the highway sections, it has been contemplated to obliquely relate the joints as shown in U.S. Pat. No. 1,740,345. However, such a construction, while reducing compressive forces, produces a lateral displacement of highway sections which has not heretofore been accceptable, or remedial.